TAMPA — Chiropractor Joseph Papia climbed to the roof of his downtown business Friday, scouting the best way to fence off the flat-topped structure before the Republican National Convention. That's when he noticed a pile of bricks and a stenciled painting of Guy Fawkes next to the number "99." Police think the bricks — and a pipe discovered Monday — likely would have been used as weapons during next week's convention. They confiscated the items at 1000 N Florida Ave. as evidence and continue to investigate. "It's disconcerting," police Chief Jane Castor said Tuesday. "But it's not surprising." Talk has been circulating about similar discoveries, but Castor declined to confirm anything. This recent discovery, along with a threatening YouTube video posted last week, hint at some of the problems Tampa could see next week. In the video, a person in a Guy Fawkes mask — a symbol of revolution that Anonymous and the Occupy movement have used — promises these groups will be "fighting for freedom" next week. They are not pacifists, a distorted female voice states. "It is a fact that the flowers and holding up signs stopped working long ago," she says. Historically violent groups expected at the RNC include Anonbloc and Black Bloc. The woman tells the public not to be afraid. These groups will not harm private citizens, she says. But Tampa police Assistant Chief John Bennett said the video's tone is threatening and could dissuade peaceful protesters from going downtown next week. "This sense of fear is an inhibitor to free speech," he said. Meanwhile, Papia said he hopes other businesses will check their roofs. Castor encouraged business owners to call police if they see anything suspicious. Papia thinks anarchists probably planned to throw the bricks down at passing motorists on Tyler Street, which will be open to traffic. His business, near the newly renovated Floridan Hotel, is nearly a dozen blocks from the established protest zone. "It is not uncommon for groups, especially those that want to disrupt or commit specific crimes, to do so away from the organized demonstrations," Castor said. Police are prepared, she said. And so is Papia. He has finalized plans to fence off his roof this week. Then, he says, he's getting out of town. Times staff writer Richard Danielson contributed to this report. Jessica Vander Velde can be reached at [email protected] or (813) 226-3433.